drivers/ata: add support to Freescale 3.0Gbps SATA Controller

This patch adds support for Freescale 3.0Gbps SATA Controller supporting
Native Command Queueing(NCQ), device hotplug, and ATAPI.  This controller
can be found on MPC8315 and MPC8378.

Signed-off-by: Ashish Kalra <ashish.kalra@freescale.com>
Signed-off-by: Li Yang <leoli@freescale.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>